This application is for a Mentored Clinical Scientist Development Award (K08) for Dr. Aristea S. Galanopoulou, sponsored by Dr. Solomon L. Mosh. Dr Galanopoulou is an MD (Medical School of Athens) PhD (McGill University) trained in Neurology and Clinical Neurophysiology at Albert Einstein College of Medicine, where she is currently Assistant Professor. At McGill, Dr. Galanopoulou was trained in Molecular Biology and in vitro gene delivery methods. At Albert Einstein College of Medicine she has used in vivo experimental methods pertaining to seizure research. Dr. Galanopoulou's long- term goals are to employ novel molecular biology based approaches to develop effective treatments for epilepsy. The substantia nigra pars reticulata (SNR) has crucial role in seizure control. Intranigral infusions of muscimol, a GABAA receptor agonist, have sex, age and region specific effects on seizures. This proposal will study the role of the potassium-chloride co-transporter KCC2 in the sexual differentiation of GABAA responsive male infantile rat SNR neurons, which determine its function in seizure control. KCC2 switches hippocampal GABAA receptors from depolarizing to hyperpolarizing. Dr. Galanopoulou's findings suggest that the level of KCC2 in the SNR may determine whether GABAA receptor activation is pro-convulsant or not and correlate with sex-specific membrane responses and patterns of estradiol signaling. These data raise the possibility of accelerating the development of efficient control systems for seizures, by over expressing KCC2 and altering the sexual phenotype of male SNR. Dr. Galanopoulou will test whether in vivo over expression of KCC2 in the SNR of PN21 male rats abolishes: 1) the muscimol-induced depolarization and calcium rise, 2) the estradiol-mediated down regulation of phosphorylated CREB, 3) the muscimol-induced pro-convulsant SNR responses, and 4) will identify other genes regulated by KCC2, which suppress the testosterone-organized muscimol-sensitive proconvulsant effects of male rat SNR. This research will entail in vivo gene delivery using adeno-associated viruses, stereotactic surgery, immunochemistry, in situ hybridization, seizure induction, gramicidin perforated patch clamp, fura-2AM imaging, confocal microscopy, stereological cell counting, DNA microarrays and statistics. Albert Einstein College of Medicine will offer the necessary mentoring, laboratory space, equipment and training opportunities to achieve these goals.